Solar heating system with overheating protection

Abstract

A simple solar heating system incorporates a heat dissipater into a heat exchange circuit for bypassing solar collectors when either the temperature or the pressure in the heat exchange circuit exceeds preset limits. In the absence of electric controllers, fluid in the heat exchange circuit is caused to bypass the solar collectors using a valve which is controlled by either the temperature or pressure of the fluid. A solar photovoltaic panel energizes a circulating pump for increasing the rate of pumping as more solar energy is available at the PV panel and decreasing the rate as solar energy decreases.

Description

FIELD OF THE INVENTION[0001]Embodiments of the invention relate to solar heating systems and more particularly to systems for use with solar water heaters that are independent of the electrical utility grid and that substantially prevent overheating of fluids circulating therethrough.BACKGROUND OF THE INVENTION[0002]Collection of solar energy for use in heating fluids, such as water, is a well known concept with rudimentary systems originating in ancient times. Modern solar heating systems typically incorporate a solar collector that converts the sun's energy to thermal energy and utilize a variety of means to transfer the collected thermal energy into the fluid to be heated, such as for residential, commercial or industrial heating applications.[0003]Solar water heaters may be combined systems or distributed systems. In the case of a combined system, a domestic water storage tank is typically mounted directly to the solar collector. Combined systems are generally not practical in c...

AI Technical Summary

Benefits of technology

[0017]In one broad aspect of the invention, apparatus for maximizing thermal energy collection in a solar collection system independent from the electric utility grid or external energy provider comprises: one or more solar collectors; a heat exchange circuit having fluid therein and being thermally connected between the one or more solar collectors and a point of use; a solar powered pump for substantially continuously pumping the fluid through the heat exchange circuit during solar energy collection; a heat dissipater fluidly connected to the heat exchange circuit and having an inlet upstream from the one or more solar collectors and an outlet downstream from the one or more solar collectors; and a valve positioned downstream from the heat dissipater which, when closed in response to a condition being at or below a maximum preset operating condition, prevents fluid from entering the heat dissipater; and when opened in response to the condition exceeding the maximum preset operating condition, permits at least a portion of the fluid in the heat exchange circuit to bypass the one or more solar collectors to flow through the heat dissipater for cooling the at least a portion of the fluid, the cooled fluid being

Problems solved by technology

Combined systems are generally not practical in colder climates as the hot water storage tank is cooled by the cold ambient air.

Direct systems are typically prone to scaling of the collector as a result of the domestic water passing therethrough.

Solar energy can only be harnessed when the sun is shining and some of the heat gained during the day is lost if the potable water or working fluid continues to circulate during nights or during periods of low solar potential.

A significant issue with solar water heating systems is how to mitigate excessive heat.

If means for releasing pressure are not provided, excess heat leads to boiling of the working fluid and the resultant pressure increases will rupture the piping or solar collector.

Often systems are deliberately under-sized to avoid the overheating challenge.

Thus, it is clear in these cases that solar collection is not maximized.

Applicant believes it is likely that there will be insufficient impetus for thermosiphon within the complex piping of Torrens, resulting in the possibility of overheating of the fluids therein despite the heat dissipation circuit.

The Torrens system is particularly unsuitable for use where ambient temperatures fall below freezing as it is a direct system.

In cases of peak insolation, sufficient heat may not be released by the heat dissipater.

Following heat dissipation, the temperature of the re-mixed working fluid may be inconsistent as the efficiency of the heat dissipater varies with atmospheric conditions.

If excessive heat dissipation occurs the efficiency of the system is reduced.

If insufficient heat dissipation occurs there remains a risk that the system will over-heat.

Loss of electrical energy will, at a minimum, cause loss of solar heating.

It can also potentially cause damage to the system should the system overheat, result in injuries such as scalding and result in collateral damage to the building such as stained walls and floors caused by overflow of working fluid from ruptured lines and the like.

In addition to requiring electrical energy to operate the solar heating system, electronic control methods are prone to component failure especially when considered in the context of the twenty-year life of a typical solar water heating system.

Failure of the electronic control system can lead to piping or component damage and collateral damage similar to that which occurs with the loss of electrical energy.

Failure to test and replace the battery system can lead to same type of damage seen with loss of electrical energy.

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